Wireless mobile communication networks continue to be deployed and improved upon given the increased traffic demands on the networks, the expanded coverage areas for service and the new systems being deployed. Cellular type communication systems derive their name in that a plurality of antenna systems, each serving a sector or area commonly referred to as a cell, are implemented to effect coverage for a larger service area. The collective cells make up the total service area for a particular wireless communication network.
Serving each cell is an antenna array and associated switches connecting the cell into the overall communication network. Typically, the antenna array is divided into sectors, where each antenna serves a respective sector. For instance, three antennas of an antenna system may serve three sectors, each having a range of coverage of about 120°. These antennas are typically vertically polarized and have some degree of downtilt such that the radiation pattern of the antenna is directed slightly downwardly towards the mobile handsets used by the customers. This desired downtilt is often a function of terrain and other geographical features. However, the optimum value of downtilt is not always predictable prior to actual installation and testing. Thus, there is always the need for custom setting of each antenna downtilt upon installation of the actual antenna. Typically, high capacity cellular type systems can require re-optimization during a 24 hour period. In addition, customers want antennas with the highest gain for a given size and with very little intermodulation (IM). Thus, the customer can dictate which antenna is best for a given network implementation.
It is a principal objective of the present invention to provide a dual polarized antenna array having optimized horizontal plane radiation patterns. Specifically, the present invention is designed to radiate in a manner which maximizes horizontal beam front-to-side ratio (20 dB minimum), and also maximizes horizontal beam front-to-back ratio (40 dB typical).
It is a further objective of the invention to provide a dual polarized antenna array capable of operating over an expanded frequency range (23 percent bandwidth).
It is a further objective of the invention to provide a dual polarized antenna array capable of producing adjustable vertical plane radiation patterns.
It is another objective of the invention to provide an antenna with enhanced port to port isolation (30 dB minimum).
It is another objective of the invention to provide an antenna array with optimized cross polarization performance (minimum of 10 dB co-pol to cross-pol ratio in 120 deg. horizontal sector).
It is another objective of the invention to provide an antenna array with a horizontal pattern beamwidth of 59° to 72°.
It is a further object of the invention to provide a dual polarized antenna with high gain.
It is another objective of the invention to provide an antenna array with minimized intermodulation.
It is another objective of this invention to provide an antenna array with an optimized aerodynamic shape to reduce wind load effect and reduce radiation pattern distortion.
It is further object of the invention to provide inexpensive antenna.
These and other objectives of the invention are provided by an improved antenna array for transmitting and receiving electromagnetic waves with +45° and −45° linear polarizations.